This invention relates to hydraulic controls and more particularly to torque sensitive hydraulic controls for variable ratio pulley drives.
It is known in the prior art transmission controls to use the torque transmitted as a control signal source for a valve member. The prior art mechanisms utilizing a torque signal have generally taken two forms, either the use of twisting deformation along the axis of a rotating shaft member or axial displacement along the axis of a rotating shaft member. Both of these forms can provide a signal indicating the amount of torque transmitted.
In the systems using deformation along the axis of a shaft, it is necessary to provide very accurate tolerance control during manufacture so that repeatability from system to system is available. In the axial displacement systems, the axial dimension along one of the drive axes must be sufficient to house the sensing mechanism and the valve mechanism. In such systems, the sensing mechanism is generally a ball and cam. In both systems, it is necessary to provide rotary seals since the valve mechanisms used therein are generally rotatable with the torque sensor or have fluid transmitted through the shaft on which the torque sensor is mounted.